To understand the history of the coastal defence system of the Ionian basin of the Mediterranean sea, as it was arranged in the territory and its architectural characteristics, it is necessary to analyse the phenomenon of fortifications widespread among Basilicata Calabria and Sicily (Southern part of Italy). The historical events and the continuous pirate raids, from the 6th century onwards, have made it mandatory to upgrade defence, making it efficient with new weapons and new coastal construction, in a suitable position of the sighting tasks, reporting and defence. Following the census operated by the historian Santoro, in particular the coastal defence, is grouped and categorized into two major categories: the first one consists of reading defences, the Towers, intended for primary protection but at the same time limited and temporary; the second one, identified by more significant characters, Fort and Redoubt, to face the enemy. The first category, stands out on the coast (Tyrrhenian sea) of northern part of Calabria, as well as on the coast of Basilicata, has quadrangular structures, with typical battlements and gun holes; while, on the Ionian side, they had a circular watchtowers based truncated cone-shaped. The most important defensive structures on the Ionian basin of the Mediterranean Sea is the Strait of Messina, which has always played in its history an important cultural and commercial role. To address this situation, between 1884 and 1914, a tactical ‘secret’ system was developed, the ‘FortinoUmbertino’, with its particular defensive system that included a long defensive trench line of about 40 km. The studies, therefore, have highlighted places of another urbanity and another memory that still summarize by small ‘military library’, a topic rich and very articulate of over 900 years of history fortified, where men and professionals of the time give us a contribution of the highest historical level on defence systems.